Vibrational non-equilibrium effects in compressed and expanding hypersonic high enthalpy flow

Abstract

Atmospheric entry capsules shaped as spherically blunted, large apex-angle cones are widely used in space missions. Measurements in a hypersonic wind tunnel and numerical simulations on these types of capsules are performed. The comparing of the results of the experiments to the numerical simulation with respect to shock standoff distance and total drag allow for validation of the implemented physico-chemical models and the chemical relaxation rates in the numerical codes. The numerical reconstruction of the flow heavily depends on the accuracy of the assumed free stream used as an inflow conditions within the numerical simulations. The free stream of the wind tunnel experiments used as the inflow is obtained from numerical simulations of the hypersonic wind tunnel nozzle; here, the experimentally determined reservoir conditions of the wind tunnel nozzle determine the accuracy of the numerically determined freestream. Summarized we can state, that the measurements of the wind tunnel reservoir conditions drive the quality of the above mentioned validation process. The paper will present the work invested into determine the uncertainties of the validation process.